In recent years, wine has been remarkably popularized, and brands, producing areas, kinds, tastes, and the like of wine are diversified. This trend has been promoting the opening of bars specializing in wine, which are so-called wine bars, and they are offering various kinds of wines that meet the tastes of customers. In this case, trying wines of a large number of brands is necessary and in addition, there are demands for selling by measure such as so-called glass wine, and therefore, it is necessary to open a large number of bottles. However, since air is mixed into wine once bottles are opened, the deterioration of wine is inevitable. This leads to such a situation that opening of a bottle is hesitated or unconsumed wine left in a bottle is wasted due to bottle opening.
As a means for avoiding such inconvenience, a liquid preserving device structured as described below has been proposed (refer to Patent Document 1). This device includes: a pressure-reducing stopper which has a fluid passage communicating the inside of a container with the outside thereof and a down-flow valve for restricting the flow of a fluid in a direction of the inside of the container via the fluid passage and which is able to install detachably on an opening portion of the container for containing liquid; a pressure-feed stopper which has a fluid passage communicating the inside of the container with the outside thereof and a down-flow valve for restricting the flow of fluid in a direction of the outside of the container via the fluid passage and which is able to install detachably on the opening portion of the container for containing liquid; a connecting portion having a fluid passage connectable to the fluid passage of the pressure-reducing stopper or the pressure-feed stopper in an airtight state; a pressure-reducing means for discharging air from the inside of the container to the outside of the container via the fluid passage of the pressure-reducing stopper or the pressure-feed stopper; and a pressure-feed means for supplying carbon dioxide gas into the container via the fluid passages of the pressure-reducing stopper and the connecting portion.
Further, the applicant of this application previously proposed a wine extracting device so structured that the wine extracting device is attached to an opening portion of a bottle with the bottle placed upside down, and the bottle is opened while insoluble inert gas is being supplied, so that only a necessary amount of wine can be then extracted by the pressure of this gas (refer to Patent Document 2).